US1795380A - Apparatus for making spiral tubing by electric welding - Google Patents

Description

March 10, 1 931.

R. $TRESAU APPARATUS FOR MAKING SPIRAL TUBING BY ELECTRIC WELDING Filed March 26 3 Sheets-Sheet 1 INVENTOR. fi/chard Jfresa u,

'/wf 4 W ATTORNEY.

R. STRESAU 1,795,380

March 10, 1931.

APPARATUS FOR MAKING SPIRAL TUBING BY ELECTRIC WELDING 3 Sheets-Sheet 2 Filed March 26 1925 I INVENTOR. I M71 55; JZ/chdfdJfrasam t.: v Qu p i W ATTORNEYS. 9

March 10,1931. R STRESA'U 1,795 38) APPARATUS FOR MAKING SPIRAL TUBING BY ELECTRIC WELDING Filed March 26, 1923. 5 Sheets-Sheet 3 I v v ia INVENTOA n I. $5 Ric/Lard Giraud,

WTNESs:

0n. ATTORNEYS.

Patented Mar. '10, 1931 UNITED STATES PATENT OFFICE RICHARD STBESAU, OF WAUWATOSA, WISCONSIN, ASSIGNOR, BY MESNE ASSIGNMENTS, TO AMERICAN ROLLING MILL COMPANY, OF MIDDLETOWN, OHIO, A CORPORATION OF OHIO APPARATUS FOR MAKING SPIRAL TUBING BY ELECTRIC WELDING Application filed March 26, 1923. Serial No. 627,599.

with the convolutions extending in the same plane while undergoing such feeding movement, in combination with welding devices in the operation of which the abutting or contiguous edges of the spirally wound strip,

as the latter is formed into a tube, are united by electric arc welding along the spiral line,

so as to constitute an integral tubular structure with a finished exterior surface.

The invention comprises also means for permanently connecting the rear end of one metal strip to the forward end of a succeeding strip by a transverse welding operation, so that as the first strip is consumed in the process of converting it intov tubular form, the operation of tube formingis not interrupted but may be continued indefinitely, by reason of the provision of means for contin uing the supply of strip material. The linear extent of the tubular product is not therefore limited by the length of a single strip, but the length of strip material available for the purposes of my invention is indeterminate. The invention comprises also means for welding transversely of the strip the abutting ends of the strips in succession and without interruption of the tube forming operation, as well as means for welding the abutting or contiguous edges of the strip during the formation of the latter into a spirally wound tube. In connection with the transverse weld ing, I provide means for clamping the contiguous ends of the strips in succession, so that the latter areheld in proper position for the performance of the transverse welding operation.

Preferably, but not necessarily, means are provided also for inserting .L-sh'aped chill strips at both the spiral and transverse welding lines, the chill strips, which furnish additional welding material, being fused and incorporated as part of the welded joint in each case. The devices for supplying the chill strip to the spiral weld are operated in consonance with the continuously operating tube forming and spiral welding devices, while those for supplying the strip to the transverse Weld are operated periodically, and only when it becomes necessary to unite the abutting ends of the succession of strips.

Provision is made also for grinding the surplus metal away from the spiral Welding line as the tube is being formed, so that a finished and smooth exterior surface is produced during the manufacture of the tube.

Means are provided also whereby the continuously formed and completed tube of in definite length may be cut into sections of predetermined length during the process of manufacture of the tube, the cutting being performed without interruption of either of the tube forming or welding operations.

Other features residing in my present invention will be more specifically referred to hereinafter, and the novelty of the invention will be pointed out in the appended claims.

In the drawings attached and forming part hereof:

Figure 1 is a plan arrangement of the devices in which my invention has been embodied.

Fig. 2 is a vertical sectional view on the line 2-2,- Fig. 1, looking from the top of Fig. 1 in the direction of the arrows.

Fig. 3 is a vertical section transversely of the apparatus on the line 33, Fig. 1, near the point where the spiral Welding is performed.

Fig. 4 is a vertical central section taken longitudinally of the tube forming and spiral welding means at the same point.

Fig. 5 is a rear view in elevation of the travelling mechanism employed for transversely Welding the contiguous or abutting ends of the succession of metal strips, the said view looking to the right of Fig. 1 and the left of Fig. 2.

Fig. 6 is an enlarged view in elevation corresponding to the view at the left of'Fig.

2, and showing in detail the arrangement of some of the devices employed in the same connection.

view showing the general Fig. 7 is a diagrammatical view in elevation showing the manner of mounting the travelling means operating in conjunction With the apparatus to cut the spirally welded tubing or circumferential lines into sections of the desired length.

Fig. 8 is a transverse section on the line 8-8, Fig. 1, showing the arrangement of the radially adjustable pressure points which di-' rect the metal strip during its tubular formation.

In the drawings, the frame 10 supports the table 11, over which passes the flat metal strip 12, which is to be automatically converted into tubular form by spiral winding, the abutting edges of the said strip being always disposed in spiral formation therefor, and united by electric arc welding along the spiral line of such winding. J ournaled in bearings in the frame 10 are positively acting, continuously driven feed rollers 13 and 14, geared so as to rotate in unison, and engaging the opposite surfaces of the strip 12, so as to advance the strip into the tube forming devices, whereby the strip is converted into its tubular form with a spiral seam. The operation of the continuously driven rollers 13 and 14 is such that the metal strip 12 is advanced at a uniform rate of speed by posi-o tive action, and is made to assume its tubular form under the pressure exerted by the feed rollers.

In order that the flat metal strip thus fed through the machine may be converted into an elongated or wide annulus of spiral construction with its edges in proximity and the convolutions thereof in the same longitudinal plane, I arrange on a bracket 15 carried by the frame 10, a tubular casing or shell 16, the interior diameter of which is equal to the exterior diameter of the tube to be produced. Adjustably mounted at one end within the tubular casing 16, but in fixed relation thereto, is a hollow cylindrical mandrel 17, the adjacent tube shaping surfaces of the casing 16 and the mandrel 17 being concentrically positioned with respect to each other, but separated by an open circular space sufficient only to permit the free passage of the strip 12 through the said space, so as to conform the convolutions of the strip into the exact annular state desired, and prevent overlapping of the edges.

As shown in Fig. 2, the bracket 15 at its outer end is curved upwardly and returned so as to form ayoke and provide vertically disposed aligned bearings for the journals 18 and 19, formed upon the casing 16. The

' casing 16 with its adjunctive devices may therefore be rotated upon its vertical axis so as to be adjusted in a horizontal plane and set at any divergent angle with relation to the line of movement of the strip 12. By means of this provision for adjustment, the edges of the strip at the time of :ompleting the spiral tubular formation may be given such pitch and be brought into such exact proximity and relation that conditions conducive tained during the operation of the apparatus. Bolts 21, 21, passing through a web 22 extended from the top of the casing 16, and threaded into the table 11 also serve to further maintain the casing 16 in its adjusted position. A guard plate 23 is mounted on the table 11, just in advance of the feeding rollers 13 and 14, a channel being formed between the table and the web 22 and guard plate 23, for insuring the proper advancing movement of the metal strip 12, thus overcoming any tendency of the plate to buckle under the force exerted by the feed rollers and resisted by the tube shaping elements of the apparatus.

The casing 16 is provided with a radial opening which is coincident with the meeting line of the edges of the metal strip in the formation of the first convolution thereof. Projecting through the said opening and slightly into the interior of the casing, is an adjusted thin metallic spacer 24, having a thickness which will produce and maintain a slight separation of the edges of the strip as the convolution is formed, the purpose in producing such separation of the edges being to enable the insertion of a welding and cooling strip 25, into the welding groove from the inside of the tube. Such welding strip 25 is rolled into the form of a J., the upstanding stem of which is forced into the space separating the convolutions of the pipe just in advance of the spacer 24, so that such welding strip may be fused into the joint in the welding operation, which commences immediately, and becomes a permanent part of the welded joint. In addition to its purpose in supplying additional metal for the welded joint, the said strip acts as a cooling medium to reduce the temperature of the parts and obviate sticking to the stationary mandrel 17 or burning the metal at the welding line. In the welding operation, the stem of thestrip 25 is fused with the edges of the coiled strip 12 and incorporated into the weld, while the base or lower flat surface forming the bottom of the strip lies interiorly of the tube against the spiral joint formed therein.

In order to feed the welding strip 25 as the and in the sleeve-27 is mounted a lateral stub shaft carrying a feed wheel 28, mounted to rotate in the vertical plane of the welding line, and which is adapted to bear against the inner side of the tube at the point where the welding is performed, to hold the welding strip 25 in proper position with respect to the space separating the convolutions of the strip 12 and the edges to be welded. An expansion spring 29 surrounds the post 26 and exerts a pressure on the 'sleeve 27, which will be sufiicient to engage the periphery of the feed wheel 28 wit 1 the interior of the tube, through the strip 25, such engagement being frictional in a degree which will effect the coincident rotation of the wheel 28 with that of the tube as the latter is being formed. The

welding strip is entered at the open end of the mandrel 17, that is, the end appearing at the top of Fig. 1, and is directed to the wheel 28 by means of a tubular guide 30,"and is automatically fed or drawn into position by the conjoint rotation of the feed wheel 28 and the spiral tube which is being formed. The casing 16 is cut away for a portion of its circumference so as to form an opening or recess 31, the sides of which may be parallel to the traveling welding line. The purpose of the said recess 31 is to provide a clearance in which theweldrod A may enter, so as to perform the welding operation upon the con-' ti uous edges of t e spirally wound strip. T e feedingwheel 28 is located immediately underneath the recess 31. The tubular mandrel 17 is clamped at its rear or inoperative end in the casing 16 by means of a bolt 32 which bridges an axially extending slit in the casing 16, so that the said mandrel may be accurately adjusted and maintained as to its 40 position in the casin The table 11 may be provided with longitudinal guides 33, 33, for properly directin the metal strip 12 into the apparatus.

, strip 12 upon being laid upon the feed table 11 is entered between the feeding rollers 13' and 14, and thereafter positively fed by Such rollers into the tube forming 1nechanism,-to be converted into a spirally wound tube, and welded to form an integral structure in the w manner before described. As a result of the great pressure exerted by the feeding rollers upon the metal -strip, the latter is forced through the tube forming devices by a positive action, and caused to follow the contour of the casing and the mandrel. The latter being set at the desired divergent an le with relation to the line of movement of t e strip, it follows from the arrangement that the metal, strip will assume .the annular form of C0 the same plane and with the edges in such contiguous or proximate relation, that the welding of such edges may be easily and completely efi'ected.

curvature to facilitate the tube, with the convolutions extending in In Fig. 8 I have shown an arrangement of radially upon t e advancin end of the metal strip 11, and to impart t ereto the desired initial assage through the tube formingdevices. e points are hardened so as to resist wear, and two of them, indicated 60 and .61, are arranged in radial openings formed in the casing or shell 16; being held in position by means of set screws threaded into the casing.. Shims may be inserted between the casing and the heads of the points 60 and 61 to secure exact adjustment. The third point 62 is arranged in a similar manner in an opening formed in the mandrel 17 and adjustment thereof'tq the desired position is effected by means ofa set screw threaded through a boss formed into riorl of the mandrel.

Wzildingdevices are now so well known that it is not considered necessary to illustrate the arrangement of the same in the present connection, but such devices may be supported the'casing 16 and participate u n in *any adiiisting movements thereof, so that the point of the weldrod A, which exemplifies the spiral welding devices, will always be traversed by the welding line in the rotation of the tube. I prefer to use a destructible weldrod, and to incorporate the molten metal flowing therefrom in the fusion of the edges of the spirally wound strip, together with the welding strip 25. But an ordinary electrode may be used to conduct the welding current and produce the arc in the welding operation, instead of a fusible weldrod, such as is preferably used by reason of the'more satisfactory results attained by the latter.

As the rear end of the first strip, 12 approaches the feed rollers, I bring into conqunction with it the forward end. of a second strip, and byv a transverse welding operation upon'the meetin ends of the two strips,'u nite them into a sing e length, so as to enable the apparatus to operate continuously in producing the tube. The transverse welding apparatus is adapted to have a longitudinal movement with the metal strips, and to maintain the weldrod in a. fixed sition with relation to'the transverse welding line.- The transverse welding devices are connected or coupled-to the strip at the right moment so as ermit forward movement therewith,

adjustable devices d to bear whi e the point of the weldr'od'is traversing e the welding line. w

The transverse welding devices are mounted in 'a'frame '34 supported on rollers, which move over longitudinal tracks-35 fixed on the frame 10 adjacent the table 11, the frame 34 bei normally held in its retracted position y means of a weight 36,.or other means, but free to move forwardly when the resistance of the weight is overcome by the clamp- .ing action exerted upon the moving strip 12.

An oscillating spacer-37, which maybe formed as a disc with opposite projections thereon, is pivoted in the frame 34 below the surface of the table 11, the axis of the spacer being parallel with the length of the table. The said s acer is rotated in one direction by means a spring 38, coiled about the axis thereof, and serving. to bring-the upper projection of the spacer above the surface of the table. The presence of a metal strip upon the tablell will depress the upper pro ection on the spacer below the level of the table, and hold it in that position while the said strip is being carried forward by the feeding rolls 13 and 14. When the rear end of the stripclears the spacer 37, the spring 38 will act to effect reverse rotation as before described. In the rotation of the spacer under the influence .of the spring, the lower rojection on the spacer will strike the end 0 a contrally pivoted lever 39, the other end of which engages a spring contact 40'and closes an electrlc circuit, which includes the coil of ainagnetically operated clamp 41. The core of the latter is provided'with a lateral extension 42 which is adapted in the energization of the coil to engage the forwardly moving stri 12. Thereupon, longitudinal movement 0 the frame 34 carrying the transverse welding devices -is instituted. The

movement of the core of the clamp 41 closes a shunt circuit so that the said clampwill 4 remain operative, although the circuit be broken "later at A pair of feeding rollers 44; designed to be brought into' action simultaneously with the initial movement of the frame 34, now commences the forward feeding movement at an accelerated rate of speed of a second metal strip, the motor operating the rollers 44 being energized in the closing of the clampin circuit.

of the frame 34, for guidance thereof. A

motor 45 mounted upon an extension of the frame 34, and inthe circuit of the clamp 41,

is operated to drive through a worm and gear,

the chill strip feedingrollers 46, the latter giving forward movement to a ram or driver 47 which will push the chill strip into its position between the contiguous ends of the strips 12. The end of the chill stri in the movement toward final position, wi rotate the spacer 37 in the opposite direction the force of the s ring 38, thus breaki the circuit at 40, although efiectiveness'o the latter is maintained through the shunt before described. The forward end of the second strip 12 is meantime being advanced into proximity'with the rear end of the first strip e frame 34also carries devices which aremeaaso has completed its forward movement, the f rollers 44 will slip over the surface of the plate. 1

In the final movement of the chill strip into position between the ends .of the tube forming strips 12, the end of the chill strip will contact with a projection on a disc 48' mounted on the frame 34, so as to oscillate in themanner described with reference to thespacer 37, the said disc 48 being rotated to a normally inoperative position by means of a spring coiled about the axis thereof. Rotation of the disc 48 in the othei'directlon by the final movement of the chill strip will cause a lower projection on the disc 48 to pass the switch 49 and momentarily close a circuit. Such closure will energize the coil of-a magnetic clamp 50, the core of which is provided with a lateral extension 51- which is adapted to engage and hold downthe for- Ward end of the second strip 12, so that both strips are now clamped to the frame 34 of the transverse welding devices. The movement of-the core of the clamp 50 closes a shunt circuit at 52, so that the clamping action is maintained during the transverse welding operation after the lower projection on the disc 48 passes by the switch 49 and the circuit is broken. Clamps 41 and 50 are provided at each side of the line of travel of the strips 12.

At the end of the feeding movement of the fihill strip, the rollers 46 release their hold upon the ram 47 so that the latter may return to initial or other means.

position by a counterweight The upper part of the frame 34 supports tracks 53, along which travela head 54 carrying the transverse welding-devices, the head 54 being motor actuated to traverse the welding line, and at the completion of the welding. operation is returned to the initial gosition by means of a counter weight 55. he transverse welding devices carrie by the head 54, and exemplified by the weldrod B,

may beof any suitable construction, such as will serve to feed a fusible weldrod 'in the ratio of the consumptionof the latter while the welding is taking place. A wi r 57, adapted to interrupt the several eeding movements and open the circuit of clamp 41 at 58, to dc-energize the coil of the said clainp, 1

- are repeated. In this welding operation, I

may use an electrode in conducting the arcing current, but a fusible weldrod is referable. The apparatus as a whole is esigned to operate continuously in the production of s irally welded metal pipe, but it is obvious t at the continued formation of such pipe will cause it to flow laterally from the apparatus in such a length as to pres'tnt a problem in taking care of the output in an eflicient manner. In .order to meet the, exigency, I have installed means whereby fl the spirally welded pipe during its production may be cut transversely upon circumferential hnes, so as to produce tubular sections of the desired lengths. Such cutting of the pipelis eflected automatically without interruption of the pipe forming and welding operations. In order to achieve the purpose of this feature of my invention, I arrange in a position parallel to the path of movement of the pipe,

a traveling carriage 65 movable on a track 66, the said carriage being provided with a counter weight 67 to hold it inretracted position, and with a stop 68 which is engaged by the forward ed e of the ipe in the outward movement 0 the lengt thereof.

Mounted also on the carriage is a bracket 69 which supports a torch 70, to which a suitable conductor may lead for conveying the conbustion element to the line on which the pipe is to be severed. The stop 68 may be in the form of a roller, mounted for rotation upon a post attached to the frame of the carriage 65, so that in the advancing! movement of the pipe section the said roller will be engaged by the forward edge thereof as the pipe is rotated, so as to advance the carriage in the same ratio. Therefore, the flame of the torch will be maintained in relatively fixed position in a line about the circumference of the pipe. With each revolution of the ipe a section thereof will be severed on the circumferential line upon which the flame of the torch plays. Upon removal of the severed section, the carriage 65 will return to its rearward position w1th the stop 68 in enga ement with the newly formed front edge o the advancing pipe. The carriage 65 may be made to control the flow of the burning mixture by convenient means-as desired, and which it is not necessary to illustrate in this connection. The relatively slow rate of rotation of the pipe during its formation, enables the flame fee to make a comparatively clean cut on the lineof severence.

\Vhile the apparatus as constructed rforms the spiral welding operation comp etcl and satisfactorily,-it occurs occasionally that a slight excess of metal is deposited by the fusing Weldrod upon the spiral welding .line, roughening the outer surface of the tube. In order to removefsuch excess of strip through is arrangement the convolutions thereon. Provision for the radial ment of the grinding wheel with relation to the exterior surface of the ipe should be made, in order thatthe wor may be most cfliciently performed.

In constructing the tube forming devices, I have found that the best results can be attained by the use of the mandrel and easing described, whichare spaced concentrically from each other a distance which is merely sufficient to permit the free passage of the the tube forming devices. By following t formed from the strip are directed absolutely as desired, and over-lapping of the edges thereof is prevented. The osition' of the spacer 24 determines the location of the spiral welding line, by lining up the edges with the point-of the weldrod. Operating together, the devices referred to insure the proper presentation of the edges of the strip in correct position for welding. The path of the strip in assuming its circular course is therefore strip, under the pressure exerted by the feed- 1 ing rollers, to closely follow the interior outline of the casing 16, and until it reaches the weldin point, it is not necessary in all cases to emp oy a mandrel as a part of the tube forming device, for the reason that the tube can be produced with the same degree of perfection by an apparatus from which the mandrel has been omitted. However, the mandrel forms a convenient element of the construction, in that it affords a support for some necessaryadjuncts.

The speed at which the apparatus illustrated may be operated in its entirety is determined by the time within which the spiral welding operation can be performed. The strip feeding rollers and the transverse welding devices for connecting the ends of a succession of strips, the latter devices having for their pur ose to constitute a continuous supply of tu e forming material, are capable of operating at a much eater relative speedin the performance of t eir functions. I may in some instances dispense with the spiral welding devices as a part of'th'e equipment of the tube forming apparatus. This will enable a very rapid be made, which in t e forming operation ma be severed into sections, as before descri with ample time for the transverse welding operations. Such sections may then be distributed to aplurality of machines c0nstructed especially to complete the tubular structures by welding along the spiral lines thereof, in the time required for the slower operation. By this means, a eater output can be secured than is possib e in a single,

. completely equipped tube forming and weld- Having thus described my invention, what I claim and desire to secure y Letters Batent of the United States, is:

1. In an ap aratus for manufacturing spirally weldecl pipe from a metal strip, a cylindrical mandrel, and a concentrically arranged tubular casing, the latter beingspaced from the mandrel at all points in the line of I movement of the strip a distance sufficient to permit free advancing movement'of the said strip through such space, the mandrel and casing being arranged at an angle with relation of the ine of travel of the strip to cause the latter in, its movement to assume a spiral form in combination with feed rollers which a tube forming device comprising a cylin-.

act positively to force the stri through the said space, and devices for wel ing the edgesof the strip along the spiral lines thus formed,

to constitute an integral tubular structure.

2. In an apparatus for manufacturing spirally welded pipe from a Hat metal strip,

drical mandrel and a casing surrounding the sameand spaced concentrically there rom to conafiitute a circular passage for the metal strip and prevent overlapping of the edges thereof, said tube forming device being arranged at an an le with relation to the line of movement of t e strip, whereby the coils of the latter arebrought into the same longitudinal plane with the edges of; the Strip in abutting proximity, and meansffor advanc ing the strip through the forming device, in combination with means for welding the stirip on the spiral line formed by the said e ges.

3. In an a paratusfor making spirally welded pipe in a flat metal :stnp, a-tube forming evice comprising a. cylindrical mandrel and a casing surrounding the same and s aced therefrom to form a circular passage or the metal strip, means for advancing the strip through the forming device, and

. omt. 5. In a tube making machine, devices for' means for adusting'the forming device at afi' angle with relation to the line of movement of the strip, whereby the coils of the latter are brought into the same plane with the edges in abutting relation, in combination. with means for electrically welding the strip on the spiral line formed by the said edgeswhile the tube is being formed.

4. In a tube making machine, devices for imparting a spirally wound tubular form to a strip of sheet metal, means for feeding the strip into the tube forming devices, a

fusible weldrod for conducting the welding current and supplying welding material'to the spirally welded joint, and means for supplying additional welding material to'the imparting a spirally-wound tubular form to a strip of sheet metal, continuously operating means for feeding the strip into the tube forming devices, means for feeding a chill str1 in the spiral winding line of the tube, an a synchronously operatin welding device to' fuse the chill strip an the edges of the sheet metal strip as thetube is formed and weld the whole into l a i tegral struc ture.

6. In a tube making machine, devices for inip'artin a spirally-wound tubular form to a strip 0 sheet; metal with the convolutions in the same plane, "meansifor feeding the strip into the for-min devices, and means for electrically welding't 'etube along the spiral line formed by theedges of the strip, in combination with automatically operating devices to weld thleiabutting ends of a succession of strips itdgpi'oduce a continuous supply of tube forming material, and means for inserting additional material in the. weld at such abutting en 7. In a machine for nraking spirallywound welded pipe, 9. mandrel and a casing supported concentrically about the same to constitute a circular passage for a metal stri means for feeding the strip intothe said passage to convert the strip into tubular form with the convolutions in the same-"longitudin'al plane and the edges in abutting proximity, and means supported on the mandrel for inserting a chillstrip between such edges, in

combination with electrical welding devices operating to fuse thesaid strip and edges and weld them together along the spiral line.-

8. In. a machine for making spirally-- wound welded pipe from a metal strip, means for converting the metal strip into tubular form with the convolutions inthe same longitudinal plane and the-edges in abutting proximity, means for maintaining the adfiacent edges in slightly separated relation, and

means for inserting a chill strip between the said edges, in combination with electrical welding devices adapted to fuse the'said stri p i forming devices,

and edges and weld them together along the spiral line.

9. In a machine for making spirallywound welded pipe from a metal strip, means for converting the metal strip into tubular form with the convolutions in the same longitudinal plane and the edges in abutting proximity, means for maintainin the adjacent ed es in slightly separated re ation, and means or inserting a chill strip between the said edges, in .combination with electrical welding devices adapted to fuse the said strip and edges and weld them together along a spiral line, the said welding devices includm a currentconducting weldrod which is fuse by the electric current, the molten metal flowing from the weldrod being incorporated in the welded joint.

10. In a tube making machine, devices for imparting a spirally-wound tubular form to a metal strip, and continuously operating means for feeding the strip into the tube in combination with synchronously operating electric welding devices for fusing and uniting the spirally disposed edges of the strip, and continuously operating means positioned at the spiral welding line for removing the surplus metal from the exterior surface of the tubes as the latter is formed.

11.- In a machine for making spirally wound tubing, means for feeding a metal strip, a tube forming device arranged at a divergent angle with relation to the line of movement of the metal strip and provided with a circular path which is followed by the strip in its advancing movement, whereby the strip is converted into tubular. form w'th the convolutions in the same plane and the edges in abutting relation, in combination with means for welding the tube exteriorly along the spiral line of the latter, and means for supplying a chill strip at the welding line interiorly of the tube for incorporation in the welded joint.

12. In a device for rolling and welding a strip of sheet metal in a spiral, an openended cylinder arranged to receive said strip on its interior; an electrode carried over the extremity of said cylinder and arranged to "form an electric arc with said strip as it emerges from said cylinder; 2. wheel arranged to contact with said strip on the interior of said spiral substantially under said electrode and means for forcing said strip into said cylinder.

13. In a device for rolling and weldin a strip of sheet metal in a spiral, an open-en ed cylinder arranged to receive said strip on its interior; an electrode carried over the extremity of said cylinder and arranged to form an electric arc with said strip as it emerges from said cylinder;- a wheel arranged to contact with said strip on the interior of said spiral. substantially under said electrode;

spring means for holding said wheel in contact with said strip and means for forcing said strip into said cylinder. 1

In testimony whereof I have si ned my name at Milwaukee this 23d day 0 1 March,

R. STRESAU.

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